Thessaloniki  is the second-largest city in Greece and the capital of Macedonia, the nation's largest region. It is honorarily called the Συμπρωτεýουσα Symprotevousa (lit. co-capital) of Greece, as it was once called the συμβασιλεýουσα symbasilevousa (co-queen) of the Byzantine Empire. It is the largest city in the wider geographical region of Macedonia, and also one of the largest cities in southeastern Europe. The Thessaloniki Urban Area extends around the Thermaic Gulf for approximately 17 kilometres (11 mi) and comprises 16 municipalities. According to the 2001 census, the municipality of Thessaloniki had a population of 363,987, while the metropolitan population has approximately one million inhabitants.